Thank you for your question!
Although I m not really professional about PC things, I can suggest the way I ve done when I wanted type characters of other languages on my PC.
If you use Windows,
Go to START------ CONTROL PANEL-------- LANGUAGE OPTION (maybe Language and Times etc etc..) ------- ADD LANGUAGES ----LANGUAGE tab, click DETAIL ------- ADD ------ find JAPANESE and ADD IME Standard ------- Apply
You change keyboard in language (ex) EN --- JP.
I found one topic about keyboard.
It might help you also
Please add comments if somebody has better idea for explanation !!